Generally, in order to extinguish an arc generated between a movable arc contact and a fixed arc contact at the time of interruption of current, a gas circuit breaker raises gas pressure of an arc-extinguishing gas in a puffer chamber and blows the arc with the pressurized arc-extinguishing gas. More specifically, a gas circuit breaker of a machine puffer type extinguishes the arc by compressing the arc-extinguishing gas in a machine puffer chamber through mechanical motion and blowing the arc with the pressurized arc-extinguishing gas. A gas circuit breaker of a heat puffer type extinguishes the arc by blowing the arc with the arc-extinguishing gas pressurized by arc heat. A system that combines the machine puffer type and the heat puffer type has also been put into practical use.
For the both types above, the higher gas pressure in the puffer chamber provides the improved current interruption performance of the gas circuit breaker. A known technique taught in Patent Literature 1 builds up the gas pressure in the puffer chamber by taking into the puffer chamber a vaporization gas generated from an arc-heated ablation material of a nozzle used for blowing of arc-extinguishing gas. This ablation material, which is, for example, polytetrafluoroethylene, is an insulation material that is decomposed and vaporized by the arc heat.
Patent Literature 2 teaches that an insulator of ablation material is mounted to an inner peripheral side of a distal end part of a rod-shaped fixed contact or an inner peripheral side of cylindrical movable contact.